In the telecommunications industry, modular plug type connectors are commonly used to connect customer premise equipment (CPE), such as telephones or computers, to a jack in another piece of CPE, such as a modem, or in a wall terminal block. These modular plugs terminate essentially two types of cable or cordage: ribbon type cables and round cables.
In ribbon type cables, the conductors running therethrough are arranged substantially in a plane and run, substantially parallel, alongside each other throughout the length of the cable. The individual conductors may have their own insulation or may be isolated from one another by channels defined in the jacket of the ribbon cable itself, with the ribbon jacket providing the necessary insulation. Conversely, the conductors packaged in a standard round cable may take on a random or intended arrangement with conductors being twisted or wrapped around one another and changing relative positions throughout the cable length.
Traditional modular plugs are well suited for terminating ribbon type cables. Typically, these plugs are of a dielectric, such as plastic, structure in which a set of terminals are mounted side by side in a set of troughs or channels in the plug body such that the terminals match the configuration of the conductors in the cable connected thereto. When the plug is inserted into a jack, the terminals will electrically engage jack springs inside the jack to complete the connection.
On the other hand, termination of standard round cables or cords poses unique assembly problems for the skilled technician. For example, termination of a round cable carrying, for example, four conductor pairs by means of an existing modular plug requires the following steps: First, the cable or cord jacket must be stripped to access the enclosed conductors. Next, because the conductors in a conductor pair are generally twisted around one another, the twist must be removed and the conductors oriented to align with the required interface. For some standardized plugs, aligning the conductors also involves splitting the conductors in at least one of the pairs and routing these over or under conductors from other pairs while orienting all the conductors in a side-by-side plane. Once the conductors are aligned in a plane, they may be joined to the terminals in the plug. However, the orientation process can result in various conductors of different pairs crossing over each other, thereby inducing crosstalk among the several conductor pairs.
Crosstalk is defined as the cross coupling of electromagnetic energy between adjacent conductor pairs in the same cable bundle or binder. Crosstalk can be categorized in one of two forms: Near End Crosstalk, commonly referred to as NEXT, is the most significant because the high energy signal from an adjacent conductor can induce relatively significant crosstalk into an attenuated receiver signal. The other form is Far End Crosstalk or FEXT. FEXT is typically less of an issue because the far end interfering signal is attenuated as it traverses the loop. Because the jack springs, conductors and the plug terminals or contacts near the jack springs are generally quite close to, and exposed to, one another in a communication plug, control of crosstalk is a paramount consideration in any plug design. Unfortunately, crosstalk in a communication plug cannot be merely eliminated. Jacks are engineered to generate a certain amount of compensating crosstalk to counter the crosstalk produced in the plug. Accordingly, a communication plug should be designed to optimize rather than just minimize crosstalk.
In addition, the technician time involved in the prior art practice of separating out the twisted pairs of conductors and routing them to their proper terminals in the plug is considerable. Even if the technician, splicer, or other assembly person is accurate in the disposition of the conductors, the time consumed by him or her in achieving such accuracy is considerable. Thus, the time spent in properly routing the conductors can add considerable cost. Where it is appreciated that thousands of such connections are made daily, involving at least hundreds of technicians, it can also be appreciated that any reduction in time spent in assembling the plug can be of considerable economic importance.
Accordingly, there exists a need for a modular plug that can terminate a standard round cable and that provides a straightforward interface between the conductors in the cable and the plug terminals, involving less assembly time than heretofore. In addition, it is desirable that such a plug be capable of optimizing crosstalk through fixing the crosstalk level during manufacture or assembly. In this context, optimization means reducing crosstalk in the plug or providing a predetermined level of crosstalk to match the requirements of a jack designed to eliminate an expected crosstalk level.